Both UPS and the FTA have raised “serious concerns” with the Scottish government about its proposal to introduce a blanket Euro-6 low emission zone (LEZ) strategy across the country.

The Scottish government said LEZs were a “potentially effective measure that could help to improve local air quality”. It added that a national framework could encourage their adoption.

But in its response to a recent consultation on the measures, UPS said it was “greatly concerned about the suggestion in the strategy guidance that vehicle owners and operators should be given a maximum of two years following the initial announcement to ensure compliance”.

It added: “Euro-6 standard vehicles were only introduced in 2014. This means that while UPS does operate some Euro-6 vehicles in Scotland, the majority of our fleet is Euro-5 compliant.

“As a result of commercially realistic replacement timeframes, it will therefore take several years for us to be completely Euro-6 compliant.”

The FTA said that the short timeframe would cause significant cost to operators and questioned why LEZs had been elevated “to a prime position above all other interventions despite there being no clear case to do so. In principle this is a bad way to make policy”.

It added: “Logistics is a UK-wide operation and the government should work with other UK authorities to have one single approach for the UK, unless a truly distinct need for Scotland can be identified and demonstrated.”

Rab Dickson, transport strategy manager at Nestrans, the transport partnership for Aberdeen City Council, said its feasibility study into an LEZ, which also included out of hours deliveries and urban delivery centres, was currently on hold while the national strategy was finalised.

“All made minor benefits, none met the overall objective of meeting the air quality strategy,” he added. “It’s a question of which packages could work together collectively.”

Last year MPs were told that benefits from London's LEZ had failed to materialise.